In recent years, the popularity of the continuous connection environment of the Internet has continued to grow, and various electrical appliances are being connected to a network. Such company or home network environments (herein after referred to as “private network”) usually access the Internet via a router having NAT (Network Address Translation)/NAPT (Network Address Port Translation) functions.
A user can connect directly (P2P connection) from outside the private network (herein after referred to as “out-of-house”) to such electrical appliances by means of a mobile terminal, and it is possible to use the contents which are stored in the electrical appliances and remote-control the electrical appliances, and also, it is possible that service providers that support the P2P connection between the mobile terminal and the electrical appliances, will appear.
In order to establish a P2P connection from out-of-house mobile terminals to electrical appliances inside the private network (herein after referred to as “in-house”), translation of the address using NAT is required, for example, it is necessary to add the entry of the in-house electrical appliances, in other words, the address and the port translation table of the electrical appliances to a NAT router as that described in Patent Document 1.
A manual port forwarding setting which uses static port mapping, and a method which uses a UPnP (Universal Plug and Play) gateway function are given as methods of adding an entry of the in-house electrical appliances to a NAT router.    Patent Document 1: Japanese Patent Application Laid-Open No. 2001-345841